Transmission and Distribution Slide.pptx

This slide help the learners to understand about the power generation, transmission and distribution of power system. This slide mainly focuses on analysis and calculation of Capacitance, Inductance and Resistance in transmission lines. The Sag and String efficiency concepts also included. Learners will learn about the characteristics and applications of various power generating techniques. this will introduce the concept of distribution system and its classification

1. The power system network consists the following major components: Generator Transmission line Distribution line Load Transformer Generation: (Generator) In generation the energy is converted from one form to other forms and it voltage level be 6.6KV, 10.5KV, 11KV, 13.8KV and 15.75KV Sending end substation: (Step up transformer) The generated power can be transmitted by increasing the voltage level to 110 KV, 132KV, 220KV, 400KV and 765KV, this stage is known as primary transmission. Receiving end substation: (Step down transformer) In this stage the voltage level is reduced to 66KV, 33KV. This level is known as Secondary transmission. Structure of Power System Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION

2. Receiving end substation: (Step down transformer) In this stage the voltage level is reduced to 66KV, 33KV. This level is known as Secondary transmission. Secondary substation: (Step down transformer) In here the voltage level is reduced to 11KV, 6.6KV and 3.3KV. This level is known as Primary Distribution. From this stage we can directly supply to the industries Distribution station: (Step down transformer) In here the voltage level is reduced to 440V, and 230V. This level is known as Secondary Distribution. From this stage we can directly supply to the Commercial and Domestic loads. Service Mains: (Distributed Transformer) From here we can give supply to the various consumers. The power system operation and planning can be done in by Load flow or Power flow Analysis Fault Analysis Stability Analysis Structure of Power System Conti… Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION

3. Over Head and Underground Lines Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION Parameter Overhead Lines Underground Cables Conductor For the overhead (transmission and distribution) lines, the bare conductor is used. For underground (transmission and distribution) cable, the insulated conductor is used. Conductor Size The size of the conductor is smaller as compared to the conductor of the overhead cables. The size of the conductor is large due to the coated insulation. Current Capacity The overhead line has a higher current carrying capacity than the underground cable.  The underground cable has a lesser current carrying capacity as compared to an overhead line. Voltage Capacity It carries a high voltage (near about the 400kV). It carries a limited voltage (not more than 66kV). Look You can easily visualize it. As these cables are underground you can not visualize them.

4. Over Head and Underground Lines Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION Parameter Overhead Lines Underground Cables Interference Overhead lines interfere with communication lines. Underground cable does not interfere with communication lines. Insulation It requires less insulation (only at the contact point of the tower). It requires more insulation (for coating the whole conductor). Outage Operation It requires low maintenance to identify the outage location. It requires high maintenance to identify the outage location. Cost The overhead line is cheaper. The underground cable is expensive. Joint Users can easily join the extra connection on overhead lines. Users can not easily join the extra connection in underground cables. Fault Very easy to repair and clear the fault. Very difficult to repair and clear the fault.

5. Over Head and Underground Lines Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION Parameter Overhead Lines Underground Cables Proximity effect The proximity effect does not affect overhead lines. The proximity effect affects the underground cables. Corona effect Corona effect finds in the overhead system. Corona effect does not find in the underground system. Environmental Impact It gets impacted by the occurrences of environmental attacks (like lightning, windstorm, thunderstorm). There are fewer chances of environmental attacks in an underground system. Real time Diagram

6. Need for EHV Transmission Increase in size of generating unit Increase in transmission efficiency Pithead steam plants and Remote hydro plants Number of circuits and land requirement Line costs Surge Impedance loading EHVAC (Above 400KV to 765 KV) Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION

7. Merits of EHV Transmission Effect of high voltage on volume of copper and on efficiency. Reduction in the cost of conductor material for given power. From the above expression we conclude that if transmission voltage increase by n-times then cost of the conductor reduces by 1/n2 times. Improvement in transmission efficiency. Reduction in percentage line drop. (Voltage increases then drop decreases) Improvement in voltage regulations EHVAC (Above 400KV to 765 KV) Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION

8. Limitations of EHV Transmission More insulation is required for the conductor and tower. More clearance is required between the conductor and the ground. More Distance is required between the conductors. So the length of cross arms used is increased. Extra care should be taken while designing the power equipments like transformer, switchgears and others to handle such high voltage. Long or bulk power transmission is not possible (Due to High installation and maintenance cost). Demerits of EHV Transmission Corona loss and Radio interference. Line support cost. EHVAC (Above 400KV to 765 KV) Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION

9. Demerits of EHV Transmission Erection difficulties. Insulation requirements. Power Station and substation equipments. Environmental aspects in EHV Transmission Route clearance through country side and forests. Biological effects of electrostatic and electromagnetic fields. Audible noise. Ozone emission. Radio and television interference. EHVAC (Above 400KV to 765 KV) Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION

10. EHV Transmission in Our Country EHVAC (Above 400KV to 765 KV) Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION 400 KV Line Dehar to Panipat Line Obra to Sulanpur line Sultanpur to Lucknow line Obra to Kanpur line Kanpur to Moradnagar line Koradi to Katwa line Srinagar to Jammu-Kashmir line 765 KV Line Anpara to Unnao Tehri to Meerut Vindhayachal to Bina-Nagda Kishanpur to Moga Monubulu to Sriperumbudur Agra to Gwalior Pichor to Mainpur

11. HVDC Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION Introduction: After the advent of rectifiers and thyristors the HVDC become popular. Simplified HVDC transmission system: For Rectifier firing angle Greater than 0 deg to less than 90 deg For Inverter firing angle Greater than 90 deg to less than 180 deg HVDC Link classification: Mono polar Link Bi-polar link Homo polar link

12. HVDC Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION HVDC Link: Mono polar link It uses only one conductor Return path may be provided by water or ground Economic Metallic return path may also be used where the earth resistance is too high Earthing of poles is done by earth electrodes, its located about 15 to 55 Km from the terminal stations.

13. HVDC Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION HVDC Link: Bi - polar link It has two conductor. One for positive polarity and another one for Negative polarity. Set of converters are used in each line. The midpoint is earthed using line Electrodes and Earth Electrodes. The voltage range is 600KV, 500KV and 400KV (+- 5% is acceptable). If there is any fault occur in one side then, this system will acts as a monopolar system. The current flow through is always same.

14. HVDC Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION HVDC Link: Homo - polar link It has two conductor. Both are Negative polarity. At present its not in use. Negative polarities are normally used to reduce the corona losses and radio interference. During faulty condition it will not acts as monopolar link.

15. Interconnection of HVDC to AC System Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION HVDC Bi-polar transmission system, where bulk power is transmitted from one point to another point over long distance. Back – Back DC link. Parallel connections of AC and DC links. Multi Terminal DC links. Applications of HVDC System: Long Distance bulk power transmission. Power transmission through underground or submarine cables. Asynchronous interconnections of AC system operating at different frequencies or where independent control of system is desired. AC and DC lines in parallel. DC transmission with AC system. Back to back HVDC coupling stations Control and stabilization of power flow in AC

16. Limitations of HVDC System Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION High cost of conversion equipments Generation of harmonics which require AC and DC filters. Blocks the reactive power. Complexity of control. HVDC links in INDIA: 765 KV Line Rihand to Delhi (First DC in india and Largest in Asia) 810Km -Bi Talcher to Kolar (1367 Km) – Bi Chandrapur to Padghe 500KV - Bi Hirma to Jaipur 600KV - Bi Korba STPS to Karamsad 765 KV - Bi Agra to Gwalior

17. Distribution System Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION Introduction: Distribution is to deliver the power from generating stations and substations to various consumers. It consists of distribution transformer which step down the voltage from 11KV to 400 V for three and 230 V for single phase supply. Classification: According to supply DC Distribution AD Distribution According to Construction Over head System Under ground system According to Connection Radial System Ring Main System Interconnected System According to working Primary distribution Secondary distribution

18. Distribution System Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION Major Components: Primary Distribution consists of feeders Radial feeder Simplest Economical Most commonly used one Used for supplying small and medium residential, commercial and industrial Radiates from secondary substation and branches into sub feeders Feeders and sub feeders uses three phase three wire system Laterals uses single phase Parallel feeder It consists of duplicate feed system shaving two radial feeders running in parallel Two feeders may originate from the same or different secondary substations. Each feeders supplies about half of the total load of the area, but has a capability to supply the entire load in the event. Loss of entire feeder will result in interruption of service until the load normally supplied by the faulted feeder. Loop feeder or Ring Feeder Tow or more radial feeder originating from the same or different secondary substations It separately routed through the load areas is known as loop feeder system. If the ends of the two feeders are tied together through normally open switching devices, the resulting arrangement is known as open loop feeder. If the ends of the two feeders are tied together through normally closed switching devices, the resulting arrangement is known as ring loop or ring feeder.

19. Distribution System Mr.C.Anandhakumar, AP / EEE, SRIT 6/14/2024 TRANSMISSION AND DISTRIBUTION Major Components: Secondary Distribution components: Distributors are conductors from which current is tapped off for supply to the consumers. It uses 3-phase 4-wire systems 400V for 3-phase and 230 V for single phase. It laid along road sides The service connection to consumers are tapped off the distributors at convenient points. Service connections may be single – phase, 2-wire circuits or 3-phase 4-wire. Radial Distributors: If a distributor is connected to supply system from one end only, its called as radial distributor. Disadvantages: Distributors nearest to the substation is heavily loaded. Due to load variation, voltage fluctuations is more at the far ends. If there is any fault occurs, there is no continuity of supply. Ring Main Distributor: A ring main distributor is arranged to form a closed loop. It may have one or more feeding points. It employs distributor which covers the whole area of supply finally retiring to the substation. Advantages: Due to load variations, the voltage fluctuation is less at the far end. Better Reliability. It gives continuity of supply, when fault occurs at any one distributor.